This invention is in the field of surgical instruments, and more particularly relates to "minimally invasive" surgical instruments such as laparoscopes and endoscopes.
As used herein, "minimally invasive surgery" (MIS) refers to surgery which utilizes instruments that penetrate the skin through a puncture or incision which is kept as small as possible given the needs of the operation. MIS devices include laparoscopic devices (which penetrate the peritoneal wall and enter the abdominal cavity; this includes instruments used in gynecology, and in sterlization procedures, and arthroscopic devices (which are used to operate on joints such as knees). Minimally invasive approaches and instruments have also been developed for thoracic surgery, including some types of cardiac surgery; although those uses are not as widespread as laparoscopic or arthroscopic surgery, such devices are gaining acceptance.
Minimally invasive surgery, as used herein, does not refer to endoscopic procedures, which normally do not puncture the skin. Endoscopic tools enter the body through a natural orifice; for example, bronchioscopes enter the chest through the nose or mouth, and proctoscopes enter the colon through the anus. In addition, as used herein, "minimally invasive surgery" excludes angioscopic devices pass through blood vessels. Endoscopic and angioscopic devices typically have flexible assemblies between the handle and the operating end, to allow the operating end to be pointed or twisted in any desired direction as it passes through channels or tunnels inside the body. Any such devices which have flexible shafts are not covered by the subject invention.
One class of devices which are used to manipulate tissue or bone during minimally invasive surgery have rigid shafts with a hand-operated handle at one end and an actuator (such as scissor blades or forceps jaws) at the other end. The rigid shaft allows the surgeon who is gripping the handle to have positive, firm control over the tissue that is being cut, pulled, sutured, or otherwise manipulated. Various rigid-shaft MIS devices are commercially available from companies such as Elmed (Addison, Ill.), Snowden-Pencer (Tucker, Ga.), and Wolf Medical Instruments (Rosemont, Ill.); these companies all publish catalogs showing photographs and other illustrations.
In general, rigid-shaft instruments used in MIS procedures can be grouped into either of two categories. In one category, which is not involved in this invention, an operating instrument (such as scissors or grasping forceps) with a very slender shaft is inserted through a channel (often called a probe channel) in a larger shaft which also carries a light source and/or a fiber optic cable for viewing. For example, a typical operating laparoscope has a shaft with an outside diameter of 10 millimeters (mm), and a probe channel with an inside diameter of 5 mm for insertion of an operating tool. These devices, which allow certain types of surgical procedures to be carried out through a single skin puncture, are sometimes called "operating laparoscopes," since they include both the scopic (viewing) components and the operating instrument. These devices are not covered by the subject invention.
The second category, covered by the subject invention, involves simpler operating tools which do not pass through the same shaft with a light source or viewing component. These are sometimes called "double puncture" instruments, since they normally can be used only in an operation that involves at least two skin punctures (i.e., the operating instrument passes through one skin incision, while the light source and a viewing instrument must pass through a second incision). As used herein, these devices are referred to as "single-tool rigid-shaft" (STRS) instruments; the phrase "single tool" distinguishes them from operating laparoscopes and other devices having more than one tool or function, while the phrase "rigid shaft" distinguishes them from endoscopes and other devices that are flexible rather than rigid.
A typical STRS device will have a shaft diameter of 3, 5, or 10 millimeters (mm), and an overall length of somewhere between 30 to 50 cm. The handles of most such devices usually fall into either of two categories; one category is usually called "scissor" or "ring" handles, while the other category is referred to herein as "plunger" handles. As implied by the name, scissor handles resemble the handles of a pair of scissors, where the two pieces of the handle are connected by a single pivot point. The pivot (usually a screw or rivet) effectively creates a lever system, with handle components (usually shaped as rings, so that a finger and a thumb can be inserted through the rings without risk of slippage) on one side of the pivot and lever components on the other side of the pivot. Plunger handles involve an internal component which slides through the shaft of a second external component, comparable to a large syringe. In one type of scissor handle arrangement, shown in FIG. xxx, closure of the ring portions causes closure of the lever components. In a different scissor handle arrangement, shown in FIG. xxx, closure of the ring portions causes the lever portions to open rather than close. In a plunger handle, an internal component slides through the shaft of an external component, in a manner comparable to a syringe. Specialized handles are available with devices such as rachets to hold the actuators firmly closed (or open), and spring-loaded arrangements that cause the actuators to remain closed until opened by the surgeon.
As used herein, "actuator" refers to the portion of a surgical instrument that actually contacts and manipulates tissue in a patient (or animal). Several types of common actuators are scissors, grasping forceps, and biopsy forceps. Scissors use sharpened blades to cut tissue in roughly the same manner as conventional scissors, although blade shapes vary. Grasping forceps include devices which grasp but do not intentionally cut or puncture tissue; for example, forceps with broad jaws (resembling pliers) are used for tasks such as pulling out gall bladders that have been surgically cut away from the liver, while forceps with narrow jaws can be used to manipulate a needle during suturing. Biopsy forceps use blade, scraper, hook, or punch arrangements to remove a small piece of tissue from a patient's body for analysis. These actuators are shown in catalogs published by suppliers such as Elmed, Snowden-Pencer, or Wolf.
The shaft of a typical single-channel rigid-shaft (STRS) instruments includes a hollow cylindrical shaft, which encloses a solid bar. The solid bar is connected at the forward or operating end to the actuator device (i.e., the scissor blades or forcep jaws), and at the rear or handle end to one piece of the handle assembly. When the handle is operated, the solid bar slides through the shaft tube and operates the actuator assembly. Various types of actuator assemblies are used. For example, the solid bar that passes through the shaft tube can be coupled, via a pivot, to one of the blades or jaws in a scissors or forceps assembly; the other blade, jaw, or anvil of the scissors remains rigidly attached to the end of the shaft tube, and the single movable blade or jaw interacts with the fixed component to create the desired result. Alternately, more complex arrangements are also available to cause symmetric (or non-symmetric) movement of both blades or jaws.
One of the most important problems facing endoscopic surgery involves contaminated and inadequately sterilized instruments, which can infect patients. Various articles and patents which discuss the various techniques used for sterilizing laparoscopes (and endoscopes) include Marshburn et al, J. of Reproductive Medicine 36: 483-487 (1991), U. Frank and F. Daschner, Endoscopy 21: 276-279 (1989), and G. Gorse and R. Messner, Infect. Control Hosp. Epidemiol. 12: 289-296 (1991). Although various techniques (such as steam sterilization, and chemicals such as glutaraldehyde) are widely used, they are inadequate to reliably kill all the bacteria, bacterial spores, and viruses that can be present in blood and tissue residues that infiltrate into surgical devices.
Bacterial spores deserve particular attention, since they pose a major threat of infection. In general, spores are dehydrated bacterial particles that are enclosed in a relatively hard casing. They are analogous to hard-shell plant seeds that can pass through the entire digestive tract of a bird or animal and emerge still capable of sprouting and growing a healthy plant. In the same way, bacterial spores have evolved in a way that allows them to resist and survive hostile conditions. This often enables substantial numbers of spores to survive sterilization using chemicals such as glutaraldehyde, or brief autoclaving, if the spores are coated by blood or tissue residues that shelter and protect the spores. If prolonged heating is used, it can damage the temper and weaken the steel used in surgical instruments.
In an effort to provide better sterilization of laparoscopes, several techniques have been developed. For example, so-called operating laparascopes (which have multiple channels in a single shaft) are designed in a way that allows a surgical instrument (such as scissors or forceps) to be removed from the probe channel. This allows the exterior of the instrument to be thoroughly wiped off, and it allows the probe channel in the large laparoscopic shaft to be rinsed out with high-pressure water. However, this technique is not available for single-channel rigid-shaft (STRS) instruments as defined above, since such devices are not inserted through a probe channel in a larger device.
Some rigid-shaft instruments have been developed which provide a rinsing channel through the shaft of the device. The rinsing channel is opened by removing inlet and outlet plugs or other devices at each end; water is then forced into the inlet end, and it passes through the interior of the shaft tube while the solid actuator bar remains inside the tube. This is partially but not completely effective in removing blood and tissue residues from inside the shaft of the device. It also suffers from various other problems; for example, in the often hurried and crowded environment of a hospital, any small components that are temporarily removed from a larger instrument can be misplaced and lost.
The subject invention discloses an improved method of constructing single-channel rigid-shaft (STRS) instruments for minimally invasive surgery. In this invention, a method is provided for disassembling the instrument so that the interior rod can be removed from inside the shaft tube. This allows all surfaces of both the interior rod and the hollow shaft tube to be rinsed, wiped, or brushed until they are completely clean. This removes all blood and tissue residue from the disassembled components, so that when the components are sterilized (either assembled or disassembled), the sterilization is much more effective and reliable.
Accordingly, one object of this invention is to disclose a single-channel rigid-shaft minimally invasive surgical instrument which can be disassembled for improved cleaning and sterilization. Another object of this invention is to disclose a method of sterilizing a single-channel rigid-shaft instrument which can be disassembled to remove the interior rod from the outer shaft tube.